[clang] [Sema] Fixed faulty shift count warning (PR #69521)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

I think this looks right, but if @shafik would take an additional look, I'd appreciate it.

Additionally, this needs a release note.

https://github.com/llvm/llvm-project/pull/69521